The present invention relates to apparatus for conveying fluids, and more particularly to improvements in apparatus for simultaneously conveying several discrete liquid streams, especially liquid streams of different compositions. The invention also relates to a machine, especially a machine for developing exposed photosensitive material, which embodies the above outlined apparatus.
A machine for development of sheets or webs of exposed photographic film, X-ray film, photographic paper or like photosensitive materials comprises several vessels each of which contains a different liquid bath. Thus, a first vessel can contain a supply of liquid developer, a second vessel can contain a fixing bath, and a third vessel can contain a rinsing agent. At least some vessels must be connected with discrete sources of regenerating liquid which is admitted to the respective vessels at a controlled rate, e.g., at a rate corresponding to the combined area of the running exposed photosensitive material which passes through the vessels per unit of time. Furthermore, it is often necessary to circulate the contents of the vessels so as to ensure uniform distribution of the regenerating agent or agents in the respective liquid baths.
In presently known developing machines, each source is connected with the respective vessel by a discrete motor-pump aggregate, and such machines further comprise means for monitoring the rate of transport of photosensitive material through the vessels and for transmitting signals which are used to operate the aggregates as a function of the corresponding rate. The aggregates can further serve to circulate or agitate the contents of the corresponding vessels. A drawback of the just described developing machines is that the numerous motor-pump aggregates contribute to the bulk and complexity, as well as the initial and maintenance costs, of the machines. Moreover, the aggregates generate considerable noise which is especially undesirable when the developing machine is set up for operation in medical laboratories wherein the development of X-ray films is carried out in the presence of physicians, nurses and other persons not directly occupied with the exposure and/or development of X-ray films. Thus, when a developing machine is set up in the office of a physician for stand-by operation, i.e., whenever the need for the exposure and development of X-ray films arises, the noise which is generated by numerous motor-pump aggregates can be disturbing to the patients, to the physician(s) and/or to persons not directly in charge of servicing the developing machine.
German Offenlegungsschrift No. 1,907,159 discloses a micropump assembly with several pumps which receive motion from a common prime mover by way of levers which can be pivoted by a rotary polygonal cam. The pumps include deformable membranes, and the assembly is intended for use in research laboratories to deliver minute quantities of liquids along several discrete paths. A drawback of this assembly is its lack of versatility and the complexity of the system which transmits motion from the prime mover to the discrete membranes.